Question

During alpha decay of a uranium atom, both alpha particles and gamma rays are emitted. The alpha particle is made up of 2 protons and 2 neutrons. An alpha particle is identical to the nucleus of helium, and is often written as superscript 4 subscript 2 baseline upper H e or superscript 4 subscript 2 baseline upper H e superscript plus 2 baseline.
A uranium atom has an atomic number of 92 and an atomic mass of 238. It is written as superscript 238 subscript 92 baseline upper U. After the uranium atom undergoes radioactive decay, releasing a gamma ray, what are the atomic number and atomic mass of the daughter product?

What are the atomic number and atomic mass of the alpha particle?

Based on the atomic numbers and masses of the resulting particles, an isotope of thorium and a helium atom remain after alpha decay of uranium-238.

Write the chemical equation that represents the alpha decay of uranium-238.

Polonium has an atomic mass of 212 and an atomic number of 84. Write the chemical equation that represents the alpha decay of polonium-212.

Radium has an atomic mass of 226 and an atomic number of 88. Write the chemical equation that represents the alpha decay of radium-226.

Next, consider beta (beta superscript minus baseline) decay. When a carbon atom undergoes beta decay, a neutron changes into a proton and an electron, which is a beta particle. The symbol for a beta particle is superscript 0 subscript minus 1 baseline e. The electron is emitted along with gamma rays.

Carbon has an atomic mass of 14 and an atomic number of 6. It is written as superscript 14 subscript 6 baseline upper C. After the carbon atom undergoes beta decay, what are the atomic number and atomic mass of the daughter product?

What are the atomic number and mass number of the beta particle?

Based on the atomic numbers and masses of the resulting particles, an isotope of nitrogen and an electron remain after beta decay of carbon-14.

Write the chemical equation that represents the beta decay of carbon-14.

Iodine has an atomic mass of 131 and an atomic number of 53, written as superscript 131 subscript 53 baseline upper I.

Write the chemical equation that represents the beta decay of iodine-131.

Sodium has an atomic mass of 24 and an atomic number of 11, written as superscript 24 subscript 11 baseline upper N a .

Write the chemical equation that represents the beta decay of sodium-24

Answer 1

1) The answer is: the atomic number is 90 and atomic mass is 234.

Gamma rays contain much more energy (most penetrating) than other waves because they have a greater frequencies.

Gamma rays are the electromagnetic waves with the shortest wavelengths (1 pm), highest frequencies (300 EHz) and highest energy (1,24 MeV).

During gamma emission the nucleus emits radiation without changing its composition, if for example have nucleus with six protons and six neutrons (carbon atom) and after gamma decay there is nucleus with six protons and six neutrons.

2) The answer is: the atomic number is 2 and atomic mass is 4 of the alpha particle.

Alpha particle is nucleus of a helium-4 atom, which is made of two protons and two neutrons.

Alpha decay is radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and transforms into an atom with an atomic number that is reduced by two and mass number that is reduced by four.

3) Nuclear equation: ²³⁸U → ²³⁴Th + α (alpha particle).

Nuclear reactions can produce new elements, because number of protons and neutrons is changed.

Thorium is in actinoid series .

Thorium (Th) is radioactive metallic chemical element with atomic number 90.

Half-life of thorium-234 isotope is 24.1 days.

4) Nuclear equation: ²¹²Po → ²⁰⁸Pb + α (alpha particle) or

212/84 Po → 208/82Rn + α.

Alpha decay is radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and transforms into an atom with an atomic number that is reduced by two and mass number that is reduced by four.

So, radium decays and new element is formed with:

a) atomic number 82 (84 -2). This new element is lead (Pb).

Lead (symbol: Pb) is a chemical element with atomic number 82, it has 82 protons and 82 electrons.

b) mass number is 208 (212 -4).

5) Nuclear equation: ²²⁶U → ²³²Rn + α (alpha particle) or

226/88U → 222/86Rn + α.

Alpha decay is radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and transforms into an atom with an atomic number that is reduced by two and mass number that is reduced by four.

So, radium decays and new element is formed with:

a) atomic number 86 (88 -2). This new element is radon (Rn).

The most stable isotope of radon (Rn) is radon-222 with a half-life of 3.82 days.

b) mass number is 222 (226 -4).

6) The answer is: the atomic number is 7 and atomic mass is 14.

Beta decay is radioactive decay in which a beta ray and a neutrino are emitted from an atomic nucleus.  

There are two types of beta decay: beta minus and beta plus.  

In beta minus decay (this example), neutron is converted to a proton, an electron and an electron antineutrino and decay atomic number Z is increased by one.  

7) The answer is: the atomic number -1 and mass number is 0 of the beta particle.

The 0 in superscript of beta particle, means that the mass number is zero and the -1 in subscript means that its stomic number is one and it has a charge negative.

Beta particles are similar to electrons and can penetrate a fraction of the way in to the skin.

An unstable atomic nucleus with an excess of neutrons may undergo β− decay

8) Nuclear equation: ¹⁴C → ¹⁴N + e⁻ (or 0/-1e) or

14/6C → 14/7N + 0/-1e.

In beta minus decay (atomic number Z is increased by one, from 6 in carbon to 7 in nitrogen) neutron is converted to a proton and an electron and an electron antineutrino.

Beta decay is radioactive decay in which a beta ray and a neutrino are emitted from an atomic nucleus.

9) Nuclear equation: ¹³¹I → ¹³¹Xe + e⁻ (or 0/-1e) or

131/53I → 131/54Xe + 0/-1e.

In beta minus decay of iodine, new element is formed with:

a) atomic number 54. Element with atomic number 54 is xenon (Xe).

Xenon (symbol: Xe) is an element (noble gas) with atomic number 54, which means it has 54 protons and 54 electrons.

b) mass number 131. Mass number is sum of protons and neutrons in nucleus of an atom.

10)  Nuclear equation: ²⁴Na → ²⁴Mg + e⁻ (or 0/-1e) or

24/11Na → 24/12Mg + 0/-1e.

In beta minus decay of sodium-24, new element is formed with:

a) atomic number 12. Element with atomic number 12 is magnesium (Mg).

Magnesium has atomic number 12, which means it has 12 protons and 12 electrons.

b) mass number 24. Mass number does not change.